If you own a home anywhere from Millbrae to Gilroy, you have probably seen a headline about the Bay Area “banning” gas water heaters. The headline is misleading in a way that matters, so let’s be precise about what the rule does and does not do.
What the rule actually says
The Bay Area Air District’s Rule 9-6 sets a zero-NOx standard for residential water heaters and furnaces. It applies at the point of sale and replacement — not to equipment already installed in your garage or crawlspace.
As the rule currently stands, the phase-in runs:
| Equipment | Compliance date |
|---|---|
| Water heaters under 75,000 BTU/hr (most homes) | January 1, 2027 |
| Furnaces | January 1, 2029 |
| Larger water heaters, many tankless and commercial units | January 1, 2031 |
One important caveat: in July 2026 the Air District published draft amendments that would push the small residential water-heater date back to January 1, 2028. Public comment closed on August 13, 2026, and the Board is expected to take up the amendments in November. So treat 2027 as the planning date and watch for the revision — don’t treat either date as locked.
What this does not mean
Your current water heater is not illegal. Nobody is going to make you remove a working unit. If your existing gas heater needs a thermostat, a valve, an anode rod or a pilot assembly, it can still be repaired after the compliance date. The rule governs what manufacturers may sell and what we may install as a replacement, not what you already own.
You are not being forced onto electricity tomorrow. You’re being given a date after which the replacement you buy will need to meet the standard in force at the time.
Draft exemptions worth knowing about
The July 2026 amendments discuss carve-outs — none of them final — for low-income owners, homes where a heat-pump unit physically will not fit, and properties where the electrical work would be prohibitively difficult. If any of those describe your house, it is worth tracking the November Board decision rather than assuming you are out of options.
The part almost nobody plans for
Here is where it stops being a plumbing question.
A heat-pump water heater is not a like-for-like swap for a gas tank. It needs somewhere to put the cold air it produces, it is physically larger than the tank it replaces, and most models want a dedicated 240V circuit. On a lot of Peninsula housing stock — the 1950s and 60s builds across Redwood City, San Carlos and Belmont especially — that lands on a 100A panel that is already carrying a modern kitchen, and sometimes an EV charger too.
So the honest sequence is:
- Check your panel capacity before your water heater fails. A load calculation takes very little time and tells you whether you have a problem.
- Measure the space. Garage corner installs that fit a 40-gallon gas tank often do not fit a heat-pump unit with its required clearances.
- Decide deliberately, not in an emergency. A tank that fails on a Sunday turns into whatever we can legally install on Monday. That is the worst possible moment to be discovering your panel is full.
This is exactly the situation where having plumbing, HVAC and electrical under one roof stops being a marketing line. The water heater, the furnace that follows it in 2029, and the panel that has to carry both are one connected decision — and pricing them as three separate emergencies is how homeowners end up overpaying twice.
What we’d suggest doing this year
If your water heater is over eight years old, get the panel checked now, while the unit is still working. If it’s under eight, note the compliance date and revisit in a couple of years. Either way you want the electrical answer in hand before the plumbing decision is forced on you.
If you smell gas at any point, leave the building first, then call 911 and PG&E at 1-800-743-5000. That one is not a scheduling question.